Why convert. Just fix your current system and stay with teh R-12. It cools
much better. R-12 is coming down in price daily. You will end up spending
as much or more to change than to fix your AC. And many conversions just
don't hold up. Stay with the R-12.

I've just had my A/C upgraded from R-12 to R-134A. The conversion kit costs
around $40 in the US, and to have a decent mechanic do this for you,
provided there are no other problems with the A/C, will cost you around $200
(kit price included). While I was told that R-12 cools better than R-134A, I
have not noticed a difference in cooling performance. Additionally, the new
refrigerant (R-134A) runs at 20% less pressure (or so I was told) than the
old refrigerant, therefore making leaks in the future potentially less
likely. Furthermore, R-12 is actually being *phased out* completely, and
will disappear from the market in a few years (aside from just driving to
Mexico or something). So it's actually a good investment if you intend to
keep your Benz for a while. Staying with R-12 may be the better option
depending on your needs, but I can actually say that I'm quite happy with
the conversion in my car and it's been keeping me cool all Summer now (in
Southern California, where I use it every day).
Daniel

Pressures are higher with R134, the amount by weight is 20%less.
+++++++++++++++++++++++++++++++++++++++
That's true....your converted system is more likely to leak with R-134.
And with the higher pressure you can expect much shorter life on your
compressor and related parts. Unless you are replacing your entire AC
system conventional wisdom says fix your R-12 system leaks and recharge with
R-12 which is coming down in price nicely as there is less and less demand
for it since all new cars are R-134 now. R-134 does a great job in factory
AC systems...the problems have been in the conversions. Many conversions
are not done properly and that's where the trouble starts. For $200 most
cars with R-12 systems can be fixed and recharged so why take the chance to
convert to R-134 just because it is cheaper to recharge?

Some cars do well with conversions, others don't. Depends on the
compressor. The GM A6 compressor in the 6.9 does not. But supposedly 107
cars do well with 134 conversions.
at 08:05 PM, snipped-for-privacy@aol.com (MCAS NV) said:

I had our '87 300D converted many years ago including new compressor and new
combo hose (which caused failure in first place). It was done by an
proessional MB independent. It has been ice cold (I live in high
heat/humidity) and trouble free.
Scott D.

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